As Anna recommended, I had a look at http://plone.org/products/vice. It works on plone3 and could have provided a solution (at least for the plone3 plumi) but.. no. It wakes every objects served also. Creepy. I guess we'll have to work on a policy of catalog metadatas. If critical, we could propose a new zcatalog (feeding catalog) that would contain only the needed info. Any idea, andycat ?

This tag specifies the artwork for your podcast. Put the url to the image in the href attribute. iTunes prefers square .jpg images that are at least 300 x 300 pixels, which is different than what is specified for the standard RSS image tag.

iTunes supports images in JPEG and PNG formats. The url must end in ".jpg" or ".png". If the itunes:image tag is not present, iTunes will use the contents of the RSS image tag.